<template>
    <div>
    <router-link tag="div"  to="/" class="header-abs" v-show="showAbs">
        <div class="iconfont back-icon">&#xe624;</div>
    </router-link>
        <div class="header-fixed" v-show="!showAbs" :style="opacityStyle">城市详情
            <router-link to="/">
                <div class="iconfont header-fixed-icon">&#xe624;</div>
            </router-link>
        </div>

    </div>
</template>

<script>
    export default {
        name: "DetailHeader",
        data:function(){
            return{
                showAbs:true,
                opacityStyle:{
                    opacity:0
                }
            }
        },
        methods: {
            handleScroll () {

                const top = document.documentElement.scrollTop;
                if (top > 60) {
                    let opacity = top / 140;
                    opacity = opacity > 1 ? 1 : opacity;
                    this.opacityStyle = { opacity };
                    this.showAbs = false
                } else {
                    this.showAbs = true
                }
            }
        },
        activated:function(){
            window.addEventListener('scroll',this.handleScroll)
        },
        deactivated:function(){
            window.removeEventListener('scroll',this.handleScroll)
        }
    }
</script>

<style lang="stylus" scoped>
    @import "~styles/varibles.styl"
.header-abs
    position absolute
    left .2rem
    top .2rem
    width .8rem
    text-align center
    line-height .8rem
    height .8rem
    border-radius .4rem
    background rgba(0,0,0,.8)
    .back-icon
      color #fff
      font-size .4rem
.header-fixed
    position fixed
    top 0
    left 0
    right 0
    height $headerHeight
    line-height $headerHeight
    font-size .32rem
    background $bgColor
    text-align center
    color #fff
    .header-fixed-icon
        position absolute
        top 0
        left 0
        color #fff
        text-align center
        font-size .4rem
        width .64rem

</style>